How can I implement a GAN network for text (review) generation?
As @Clement mentions, text_gen_description gives a good overview!, but the paper seqGAN paper describes the REINFORCE approach more in depth, as they are the first to do it (i believe). This is probably the approach most take now of days when going the GAN route.  

Note that just basic MLE training has shown promise with openAI's GPT2. When i need a text generator, fine tuning one of the provided models is usually my goto.  

Also if your looking for seq gans code base (you asked for example code) here is is: git repo

Good Luck!